Thanks flux,
OK the turbine is running at the right rpm. The frequency and volts are fine... Just not enough amps going into the load controller. All phases are balanced coming out of the AVR. It looks and feels like a 30kW system... Its just producing less than half that. I have no power factor measurement, so can only give you kVA. I have no dynamometer, so can't measure the turbine shaft power. The pressure guage on the penstock suggests the pressures ok... but the gauge is definately overreading slightly, so I guess its possibly questionable.
I would have liked to take the top off the turbine to check the runner, as apparently several pythons have been through it, but we were out of sealant and it leaks like crazy otherwise (yes there is a trash screen, but the I suspect the operators have turned it into a snake trap, as the turbine does such a neat job of turning 12ft reticulated pythons into bite-size snake mcnuggets). It's making all the right noises, and the bearings are running at normal temp. The operators swore blind it hasn't been damaged.
Now I think probably some or all of the shortfall is the fault of the turbine, as the generator appears to be running smoothly (I can't think of a problem with the generator that would show as an evenly balanced reduced power output...) What I don't know is what kind of generator efficiency I should be expecting... I thought a quality generator was good for 75% at 25% load and 0.8pf, so would have hoped for an efficiency of around 60%+? (I have no basis whatsover for that guess) that would mean the pulleys delivering 14.5kVA/60% = 24.2kW, or a turbine shaft power of at least 25.5kW, or a turbine efficiency of:
(actual power: 25.5kW) / (available power: 200 (l/s) * 30 (m) * 9.81)
or 43%... Which is dismal! On the other hand, if the turbine is running at 75% efficiency, then the generator is running at around 14.5/(58.9*0.95), or 26% efficiency - which is equally depressing... If its the turbine, then I guess it must be damaged and will need to be remachined. If its the generator, then its probably just a characteristic and we'll have to consider a less oversized unit and maybe an expensive run-away prevention system.
So if I understand you right, if the generator is working too hard against the power factor, that'll show as a voltage drop?
The MHP is at a pretty inaccessible site so next time I visit I want a pretty good idea of what, if any, remedial work is needed before I depart.
Thanks for your help